Bread and spaghetti consumption in Italy today is calculated as 50% of the average total caloric ration for an adult (Enciclopedia Medica, USES, Edizione Scientifica, Edit. 1973, pages 1123-1138).
Wheat flour which contains 8-13% of protein is the principal ingredient and the rest (87-92%) is mostly starch and organic and inorganic compounds.
While starch supplies the most calories, the utilization of proteins (above all gluten, which represents 80-85% of total wheat endoplasmatic proteins) by the organism is still unclear (Hove, E. L. and Harrel, C. G., Cereal Chem., 20, 141, 1943: Bricken, M. et al, J. Nutr. 30, 296, 1945; Floridi, A e Fidanza, F. in Seminario sulle Metodologie di Valutazione della Qualita Biologica delle Proteine, CNR, page 67, 1978; Osborn and Mandal, J. Biol. Chem. 20, 351, 1915, 22, 241, 1915).
Recent studies on the digestion of gluten by proteases from different sources have clarified some fundamental aspects-for a better understanding of this protein (Menesini Chen, M. G. et al in Congr. Naz. della SIB, page 189, 1986; Chen, J. S. et al in. "IPRA Third Sub Project: Conservation and Processing of Foods-A Research Report (1982-1986)", CNR, Roma, pages 207-209, 1986; Menesini Chen, M. G. et al, Abst. in 33.degree. Cong. Naz. SIB, Brescia Gardone Riviera, 26-28/09/87, page F6, 1987; Pagani, S. et al, ibid., page F5, 1987). Some results of this research published elsewhere as well as already known data (Chen, J. S. et al in Use of Enzyme in Food Technol., ed. P. Dupuy, Lavoisier, Paris, page 389, 1982; Italian Patent Appln. No. 49557A/82; Menesini Chen, M. G. et al in "Aggiornamenti sull'Impiego di Preparazioni Enzimatiche nell'Industria Alimentare N.degree. 22", Edit. G. F. Montedoro, 1988, IPRA del CNR, Roma, pages 279-288) have suggested to us that the proteases of mammalian origin such as pepsin and tripsin (swine) have scarse proteolytic activity on wheat gluten above all when cooked (see also Hansen, L. P. et al in Protein Nutritional Quality of Food and Feeds, Edit. Mendel Friedman, Part 2, Marcel Dekker, Inc., New York, pages 393-415, 1975).